It is Supergirl versus Superman to kick off the season 2 finale. Why is Superman seemingly under the control of Rhea? Rhea infected Superman with silver kryptonite that caused him to face his biggest fear and that is Zod attacking Earth. Superman sees Supergirl as Zod taunting him. Their epic battle goes from the Daxamite ship to the streets of National City ending in a fountain where Kara manages to knock out Superman. Alex rushes to Kara’s side to make sure that she is okay.

When Kara wakes up, she basked in the warm glow of sunlight and wakes up next to Mon-el. Kara just wants to have a lie-in with Mon-el and tells a story of how her mother gave her the necklace she wears. In reality, Kara is in the Fortress of Solitude. Clark is there and he is okay and free of the Silver Kryptonite. Clark uses the Fortress archives to find a way to defeat Rhea.

Back at the DEO, Winn fanboys over Superman. Clark meets Mon-el and approves of him dating Kara. We then see Kara reach out to Rhea to invoke a trial by combat between the two. This is enough to cause Rhea to power down the weapons on the Daxamite ships. If Kara wins, then Rhea and the Daxamite leave. If Rhea wins, then New Daxam is a reality.

Meanwhile, Lilian and Lena play the blame game on trusting Rhea. Eventually, Lilian realizes that Lena is key to getting rid of aliens and asks her to figure out how to use Lex’s weapon that he developed to get rid of Superman.

Back at the DEO, J’onn is still in a coma but a vision/visit from M’Gann and a kiss gets him to wake up nad back in the fray.

With the media attention around Supergirl versus Rhea becoming over the top, Clark and Kara go to Cat, who has taken her place back at CatCo barking orders, to get her to get the press to tone down the sensationalism of the coverage. Cat then asks Clark to get James to stop being Guardian less he get killed.

Lena and Lilian then call to meet Superman and Supergirl. Lena lets Supergirl know that she can make Lex’s weapon radiate lead instead of Kryptonite into the atmosphere. This will cause all the Daxamites to leave Earth including Mon-el. Lena asks if Supergirl knew that Mon-el and Kara were dating. Supergirl simply replies that Lena get to work on the weapon.

Back at the DEO, Clark and Kara let the team know Lena’s plan. Mon-el wants them to use it in case Rhea wins even knowing he will have to leave. Kara and Clark then practice fight. Kara wonders if she can have it all (family, career, friends and love). Clark tells Kara she can and just has to work at it. Clark says that when he fights, he fights for Lois in his heart and Kara should use the people in her life as he secret weapon.

We then go to the fight between Rhea and Kara. Mon-el has come with her for moral support. The two women then engage in a fight for Earth. As the fight continues, it looks Rhea has gone back on her word as the Daxamite ships are targeting buildings including CatCo. The Martian Manhunter and Superman go out to try and stop the Daxamite soldiers and stem the chaos. Joining the fight is M’Gann who has brought some friendly White Martians.

Meanwhile at L Corp. Winn has helped Lena complete the weapon. Lilian goes to use it but realizes that Lena has only made it that Supergirl can use it.

Supergirl and Rhea continue their fight. Because Rhea’s blood courses with Kryptonite, this weakens Kara and Rhea gives it to Kara. With encouragement from Mon-el, Kara turns on the weapon. The Daxamites have a hard time breathing and beam up and leave Earth. Rhea is also incapacitated and eventually crumbles into dust. And missed opportunity where we won’t get a Dean Cain and Teri Hatcher reunion. I was hoping Rhea survived where we still could have that opportunity.

With lead in the atmosphere, Mon-el has to leave. Kara begs Alex to figure out something so Mon-el can stay but alas nothing can be done. Kara then brings Mon-el to an open field where his space ship is located. Before Mon-el gets in, the two confess how each are better for knowing each out. Kara confesses to Mon-el how he has made her happy and tells him she loves him and wishes she had said it sooner. Mon-el professes his love too. Kara then gives Mon-el her mom’s necklace and he gets in and flies away.

At the DEO, Clark tells Kara that he has to go back but that he is proud of her. Clark says that he could not have made the same decision as Kara did to give up her love to save the world. Kara tells Clark to say hi to Lois and he flies off. Alex then check on Kara to see if she is okay. Kara just wants Alex to be there for Maggie. All Kara cares about is that the people she loves are happy like her and Maggie, Winn and Lyra, Clark and Lois and J’onn and M’gann.

Speaking of our Martians, M’gann heard J’onn telepathic plea for her help and returned to him. The two share a kiss.

On another relationship note, Alex asks Maggie to marry her and while we don’t know the answer, we see Maggie have a huge grin on her face that I can only assume it is a yes.

Back at CatCo, Cat notes the sadness in Kara who admits she was in a relationship with someone but that it failed. Kara wonders if she can ever be happy as everyone around her are in happy relationships. Cat gives her some advice on how to get over her heartbreak and notes how great her journalism career has been over the year. Kara then sees some trouble brewing and leaves to deal with it. And Cat seems to know that Kara is Supergirl. The door seems to be open for Calista Flockart to return as a series regular for season 3 as there is no mention of Cat leaving again. Please make that so, I really have missed the great advice Cat gives to Kara/Supergirl.

As Supergirl flies around National City, we see Mon-el on his ship clutching on Kara’s necklace. We then see a portal open up and the ship gets sucked in. We then flashback to 35 years to the day Krypton died. We see baby Kal-el get on his ship and Kara on her ship fly away.

We then move to another part of Krypton where another baby is placed on a ship that looks like Mon-el and two women saying how the baby will grow into something powerful. So did Mon-el travel back in time and is being re-sent to Earth this time as a villain?

I am so confused but I do hope this isn’t the last time we see Chris Wood as Mon-el. I totally loved Mon-el and really loved him and Kara together.